static: remove unused pages

There are more potentially unused pages, but these are unlikely to
become relevant or reusable in the near future, so remove them.

static/.well-known/matrix/client

@@ -1 +0,0 @@
-{"m.homeserver":{"base_url":"https://matrix.grapheneos.org"}}

static/.well-known/matrix/server

@@ -1 +0,0 @@
-{"m.server":"matrix.grapheneos.org:443"}

static/.well-known/security.txt

@@ -1,24 +0,0 @@
------BEGIN PGP SIGNED MESSAGE-----
-Hash: SHA256
-
-Contact: mailto:security@grapheneos.org
-Canonical: https://grapheneos.org/.well-known/security.txt
-Encryption: data:application/x-age-public-key,age1dcftzgq00ykgwvxl5te6d5clqgx75h2g54c0u8gjc43mcnea7p7q3ma0yx
-Expires: 2026-03-01T00:00:00Z
-Preferred-Languages: en
------BEGIN PGP SIGNATURE-----
-
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-YUQZ1j6yElVXiBA9FJg1vpaWqPFeSEmi8X0c0ef5tdNKCai1c2/arhELK4msB3ih
-0Wd7MIukudGvH7Xjfb+H8EZ53OTg/3pAhNdf5E7apwlgNPdp/XPK3Uen+8o0wV4r
-cQRNBD0gGA8kyEtYfcgndFo5kVkptOZB4OLx7A9wxjDsfMYduknuTGyniZH2DBlH
-S/H0aWaoLSO2FCFT7OIkXxYTjXdbKZwgtPf5ba6gCpDL/aXrjIPeqHtmo/l2ruhx
-sc6TYiSHBQuFqQg+X2/49GxDap6k13an5ZiRPUw5CoJl3r3Ztg6ZKu4EiFmLjJ5K
-AliaN0hjwqxH0AbMc95DLUZ1oRNpk17dlcXl/Fgk7ZI/6GWEqOhEkzf3je9GrZJR
-53OTDvcarq+rS8kcZ/bSxoBLaZNcNes3kcinaCnGCTjFPgoy2f6CtuuA37KwMc0V
-TMGaKqRMUCj+lJtdM2HuY0FvWMWjrDKdPrprUx8/umrAa0XPX2k=
-=WcPV
------END PGP SIGNATURE-----